<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body {
            background: url('http://csssecrets.io/images/stone-art.jpg');
        }
        div {
            border: 10px solid hsla(0,0%,100%,.5);
            background: white;
            /*background-clip: padding-box;*/

            /* styling */
            max-width: 20em;
            padding: 2em;
            margin: 2em auto 0;
            font: 100%/1.5 sans-serif;
        }
    </style>
</head>
<body>
    <div>
        Can I haz semi-transparent borders? Pretty please?
    </div>
</body>
</html>